Terror suspects, who upon trying to enter the country should immediately be quizzed by counterterrorism officers, have been breezing straight through passport control at Heathrow, according to a newspaper report.

Since the start of July, with just two weeks to go before the Games begin, several suspects on the Home Office “watch list” have entered the country through the London airport without being interviewed, a border control officer claimed.

He said that the problem lies with inexperienced staff being hurriedly drafted in to keep queuing times down for the Games, which begin on 27 July.

He told The Observer: “It's all new faces. The rest of the staff, I have no idea where they have come from, how long they are here for, what their background is. These are people who have been forced by their own department to come here."

In a statement to Sky News, the UK Border Agency claimed measures were in place to stop potentially dangerous individuals entering the country.

It said: “Contingency staff will operate individually, but are supported by experienced border force officers at all times.

“If they have any concerns or questions they are told to escalate those concerns immediately.”

However, former border control officer Chris Hobbs, wasn't convinced and described the situation as "a nightmare”.

He told Sky News: “It doesn’t surprise me. This problem has been running since October. This is a storm that’s been brewing for a while.

“They’ve got rid of experienced officers, made them redundant, now they’re stuck, so they’re bringing in people with very little experience who can’t do the job having done two or three days’ training.

“It’s a nightmare. The system is in meltdown.”

The revelation comes just days after G4S, tasked with providing a large proportion of security for the Olympics, admitted that it was unable to provide the required number of stewards.

To make up the shortfall thousands of military personnel have had to be drafted in.